Freeze-out or freeze-in during a period of early matter domination can yield the correct dark matter abundance for small values of the velocity-averaged annihilation cross section, ? σ ann v ? f < 3 × 10 ? 26 ? ? cm 3 ? s ? 1 . However, in a generic nonstandard thermal history, such a period is typically preceded by other phases. Here, we study production of dark matter in a simple postinflationary history where a radiation-dominated phase after reheating is followed by an epoch of early matter domination. Focusing on the freeze-in regime, we show that dark matter production prior to early matter domination can dominate the relic abundance in large parts of the parameter space, including weak scale dark matter masses, and the allowed regions are highly dependent on the entire postinflationary history. Moreover, for a very broad range of ? σ ann v ? f spanning over several decades, dark matter particles can start in chemical equilibrium early on and decouple during early matter domination, thereby rendering the relic abundance essentially independent of ? σ ann v ? f . We briefly discuss connections to different observables as a possible means to test the elusive freeze-in scenario in this case.
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机译：在早期物质统治期间冻除出或冻结可以产生对速度平均湮灭截面的小值的正确暗物质丰富，？ Σannv？ F <3×10？ 26？还cm 3？ s？ 1。然而，在通用的非标准热历史中，这种时期通常在其他阶段之前。在这里，我们在重新加热后的辐射占主导地相之后的辐射占主导地相之后，研究了暗物质的生产。专注于冻结制度，我们表明早期物质统治前的暗物质产量可以在参数空间的大部分中占据遗物丰富，包括弱尺寸的暗物质质量，并且允许的区域高度依赖于整个后波动历史。而且，对于非常广泛的？ Σannv？ F跨越几十年来，暗物质颗粒可以在早期占据占据期间早期逐次开始于化学均衡，从而使遗物丰富基本上独立于？ Σannv？ F 。我们简要讨论了与不同观察到的连接，作为在这种情况下测试难以捉摸的冻结情景的可能手段。
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